Piston



W. SIMPKIN.

(No Model.)

PISTON.

No. 396,004. Patented Jan; 8, 1889.

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01a. ital} W 775 A UNITED STATES PATENT @EEicE,

YILLIAM SIMPKIN, OF RICHMOND, VIRGINIA.

PISTON.

SPECIFICATION forming part of Letters Patent No. 36,004, dated January 8, 1889.

Application filed March 10, 1888.

To all whom it may concern:

Be it known that I, WILLiAM SIMPKIN, a

citizen of the United States, residing at Richmond, in the county of Henrico and State of Virginia, have invented certain new and useful Improvements in Pistons; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to steam-pistons provided with expansible packing-rings; and it consists in constructing the helicoidal spring, of metal or other suitable material, employed for expanding the packing, with longitudinal corrugations or their equivalents on its bearing-surface, thus securing spaced points for contact against the packing-rings around the helicoidal winds of the metal strip or other material of which the spring is formed, the same forming two or more circles of contactpoints in different planes at right angles, or nearly so, to the longitudinal axis of the piston, for acting against the separate sections of the ring-packing, this construction reducing the amount of frictional impact and giving increased strength and elasticity to the spring, while relieving this style of spring from the serious objection of becoming stuck, jammed, or bound, and thus rendered incapable of performing its proper functions and of requiring the piston to be taken out for the purpose of relieving the spring whenever it becomes stuck orbound in the packingring.

In the accompanying drawings, l igurel is an elevation of the improved helicoidal spring detached from the piston. Fig. 2 is a central section of the improved piston, its red being shown in elevation; and Fi 3 is an end view of the same, the ftdlower and one of the pack- I face a continuous circle, and this whether the ing-rings being removed.

In the accompanying drawings, A represents an ordinary piston-head, B its follower, and C 0 its packing formed with two ringsections. It is usual to employ for expanding the packing-rings C C an uncorrugated helicoidal spring, D, of metal or other suitable material, within the packing-rings, between the rings 0 C and the piston-head A,

and if this spring would always operate without becoming stuck, jammed, or bound in the piston-rings it would be a very desirable eontrivance, because it expands in an outward or radial as well as in a longitudinal direction, thereby pressing the rings out against the surface of the bore of the steam-cylinder, as well as against the flange and follower of the piston-head; but it has been found that this spring as heretofore constructed would, under some circumstances, not operate, on account of its becoming bound in the pistonring, due to the large amout of frictional impact surface presented .by itself to the rings, an d this surface being a continuous unbroken one. To overcome this diflieulty I have constructed the spring D, which maybe of metal or other suitable material, with corrugations, as (I d, longitudinal with the axis of the piston and upon each of its helical winds, as illustrated in the drawings. The spring thus formed with corrugations is stronger and more elastic than the plain-surfaced spring hereinbefore rcferrml to, and at the same time it presents numerous spaced points, d, for coming in contact with the packingrings, and thus is freed from a temlency to become stuck in the packing-rings by reason of too great frictional impact against the rings. The spring, as will be seen, beingcorrugated on two or all of its helicoidal winds, is enabled to present two or more circles of spaced points, as a: it, of contact, and thus both of the packing-rin gs U C can be touched and acted upon alike by the one corrugated helicoidal spring, but in different planes.

Any desired number of packing-rings and a spring having any desired number of helicoidal winds, and corrugatml, as described, may be employtal.

I make no claim upon a spring packing-ring of helicoidal form which has its bearing-sureross-sectimial form of such spring is rectangular or semicircular and solid or hollow; neither do I claim a simple split packing-ring of cylindrical form and corrugated on its contact bearing-surface, such ring only being capable of bearing with its corrugations against a single circle of packing, and not with one series of corrugations upon one circle ot' packing in a given plane and with. another series (If its corrugations upon another circle of packing in a different plane, and such ring also not being expansihle in a longitui'liual dircci ion against the flange and Follower ot the piston-head. My improved piston combines in the same structure the advantages of the llclicoidal spring and the advantages oi? the corrugatimls ol the simple split ring, and thus lfurnislles a new article of manu laetiu'e, possessing increased utility over 1 either of the separate structures heretofore l employed.

What I claim is- 1. The 'helicoidal spring I), li'ormw'i with r corrugations t7 (1 on its hearing-s11rface for cxpandin piston-packing, said circles of corrugztiions being adapted for hearing on dif- In testimony whereof I hereunto afiix my 30 signature in presence of two witnesses.

WILLIAM SIMPKIN.

Witnesses:

.T. SAMUEL PARRISH, JAMES; 'L. ANDERSON. 

